I think I went off to make a cup of coffee IRL which is why I stayed in that room longer than needed ('Now brother step into the cart!')
e.g. the bit where I hide behind behind a headstone in the graveyard is by no means reliable (maybe 80%?)
Thanks to HN the view count on YouTube has increased dramatically! If it gets past 1000 I'm going to have to record and upload the final section with the combine troops.
EDIT: assuming that is still possible: Valve have made some changes for the twentieth birthday which I noticed today.
e.g. there's more grass and bizarrely the lift button has switched to the other side of the elevator